In recent years, disk drives, such as magnetic disk drives, optical disc drives, etc., have become widely used as external recording devices of computers and image recording devices.
In general, a disk drive, e.g., a magnetic disk drive, comprises a magnetic disk in a case, spindle motor configured to support and rotate the disk, head actuator that supports magnetic heads, circuit board unit, etc. The head actuator comprises a head gimbal assembly, which comprises a suspension supporting the magnetic heads and a conductor trace that electrically connects the heads to the circuit board unit.
In modern disk drives, such as optical disc drives, an interleaved structure that enables low-impedance signal transfer is introduced into a conductor trace to cope with a high transfer rate. The conductor impedance can be reduced by using the interleaved structure and alternately parallelly arranging conductors through which currents flow in opposite directions.
In the case where the above-described interleaved structure is applied to a magnetic disk drive, it is believed that the highest impedance lowering effect can be obtained by installing the interleaved structure at a limiter portion of the conductor trace near a slider so that all channels on the suspension are interleaved. However, the interleaved structure requires use of a metal plate that relays signal lines. If the interleaved structure is installed, therefore, the limiter portion of the conductor trace is inevitably enlarged. Consequently, the amplitude of vibration of the limiter portion increases while a magnetic head is being unloaded or if it is jolted when not in operation, and components interfere with one another during assembly. Thus, a ramp cannot be miniaturized.